Transporte eletrônico em sistemas de baixa dimensionalidade com interação elétron-fônon e campos elétricos

• Autor(a) principal: Ranciaro Neto, Adhemar
• Data de Publicação: 2016
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Repositório Institucional da Universidade Federal de Alagoas (UFAL)
• Texto Completo: http://www.repositorio.ufal.br/handle/riufal/1459
• topic: Transporte Eletrônico; Desordem não correlacioanda; Campo Elétrico; Ondas acústicas; Elétron-fônon; Rede de Morse; Electronic transport; Uncorrelated disorder; Electric field; Acoustic wave; Electron-phonon; Morse lattice; CNPQ::CIENCIAS EXATAS E DA TERRA::FISICA

In this work we studied electron dynamics in two 1-D distinct systems: (1) anharmonic lattice with electron-phonon interaction under the effect of a static parallel electric field and (2) harmonic alloy with uncorrelated diagonal disorder, electron-phonon interaction and under the effect of surface acoustic wave (SAW). In both cases we used quantum mechanics formalism for the electron and a classical Hamiltonian for chain vibrations. Moreover, electron-phonon coupling was described by a transfer energy function which depends on relative distance of nearest neighbor ions. We developed numerical calculation employing Taylor truncated expansion method for Schrödinger's equation time evolution operator and other two for lattice deformation (Euler and finite difference). Results (1) point out to the existence of a competition among electron-lattice coupling and electric field. The former promotes a electron-soliton pair formation, which moves along the chain and the latter traps electron around initial position generating Bloch-like oscillations. On system (2), association between SAW and eletron-phonon interaction promotes the breakdown of Anderson localization and charge transport even in a high disorder level. We had acceptable numerical tolerance and our calculations are in agreement to the theory.